Shasta Lake, also popularly known as Lake Shasta, is a reservoir in Shasta County, California, United States. It began to store water in 1944 due to the impounding of the Sacramento River by Shasta Dam, the ninth tallest dam in the United States. Shasta Lake is a key facility of the Central Valley Project and provides flood control for the Sacramento Valley downstream of the dam. Water outflow generates power through the Shasta Powerplant and is subsequently used for irrigation and municipal purposes.